The camellia adds a dash of color to your landscape when other plants have faded and died. Camellias are an evergreen shrub that bloom in the late fall, throughout the winter and into early spring. Flowers are large and range in color from white, pinks and deep reds. Camellias thrive in USDA Zones 7 and 8; cold hardy varieties grow in Zone 6. Although camellias are relatively healthy plants, they are susceptible to several diseases.
Camellia Flower Blight
The dampness of spring leaves the camellia susceptible to camellia flower blight. Caused by the fungus Ciborinia camelliae, flower blight first appears as small brown blotches on flower petals. The blotches expand and within two days the camellia blooms turn brown, wither and drop from the plant. Stop the spread of camellia flower blight by removing the dead flowers from the shrub and raking up fallen leaves, blooms and twigs from around the infected tree. Destroy all infected matter and remove and replace old mulch that surrounded the shrub. Use a foliar fungicide spray every other week to destroy the fungi. Always follow manufacturer directions when using chemical treatments.
The branches of the camellia shrubs are vulnerable to canker disease that is caused by the fungus Glomerella cingulat. Canker is one of the more serious diseases that affect the camellia shrub. Infected branches split and develop gray splotches that turn into concave pink cankers. The cankers surround the stems and branch of the shrub. Soon the leaves on the affected branch turn yellow and droop, and eventually the diseased area of the shrub dies. Prevent canker by keeping camellias in good health. Avoid injuring shrubs, properly fertilize the shrubs and plant them in well-drained soil. Remove all infected branches and disinfect tools when finished. Treat plants with fungicide during leaf drop and after after heavy rains. Follow all manufacturers' instructions when using fungicides.
According to North Carolina State University, camellias are shallow-rooted shrubs that don't like wet roots and may develop root rot if they are not planted in well-drained soil. Root rot is a fungal disease caused by Phytophthora cinnamomi; it often leads to the rapid death of the camellia shrub. Signs of root rot are brown roots, yellowing leaves, stunted growth and the all-over wilting of the camellia. Prevention is the only real way to stop root rot. Plant camellias in areas with good drainage. Root rot is not cured with fungicides, but when applied to surrounding soil, fungicides can stop the spread of the disease. Follow manufacturers' instructions when using fungicides.
Small bumps that appear on the underside of leaves and on stems is a sign that the camellia is suffering from oedema. Oedema occurs when the plants roots absorb excessive amounts of water too fast, allowing too much water to build up in the leaves. The bumps are actually tiny galls that are greenish-white at first, but eventually turn brown as they spread over the entire surface of the leaf. According to Clemson University, oedema is not caused by insects or a disease but by over-watering plants during damp, humid, cloudy condition. Water plants less often during rainy, humid periods and on days with little sun. Don't overcrowd plants; sufficient air flow helps prevent oedema.